This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to Japanese Patent Application No. 2002-090250 filed on Mar. 28, 2002, the entire content of which is incorporated herein by reference.
The present invention generally relates to a variable valve timing control device. More particularly, the present invention pertains to a variable valve timing control device for controlling a valve timing of intake and exhaust valves for an internal combustion engine.
A known variable valve timing control device is disclosed in Japanese Patent Laid-Open Publication No. 2001-355468. The variable valve timing control device disclosed in Japanese Patent Laid-Open Publication No. 2001-355468 includes a rotation member unitary fixed to a rotation shaft for opening and closing valve rotatably assembled to a cylinder head of the internal combustion engine, a rotation transmission member engaged to the rotation member to be relatively rotatable, vanes provide on either one of the rotation member or the rotation transmission member, hydraulic pressure chambers formed between the rotation member and the rotation transmission member and divided into an advance angle chamber and a retarded angle chamber by the vane, and a detection member for detecting a relative rotation phase between the rotation member and a crankshaft.
With the foregoing known variable valve timing control device, the detection member is fitted into a cylindrical concave portion formed on the rotation member and is sandwiched between a rotation shaft and a tightening member by a screw connection of the tightening member and the rotation shaft. The detection member is formed by any one of unitary stamping and cutting, sintering unitary molding and cutting, or coupling of two parts.
Notwithstanding, with the known detection member, it is required to increase the precision of a fitting portion and a tightening seat surface, and thus the manufacturing cost is increased by for example, cutting. In addition, because the tightening force of the tightening member is received by the tightening seat surface, it is required to apply the material with high critical surface pressure or it is required to apply the heat treatment, the manufacturing cost is increased. In order to avoid the rotation of the detection member along with the rotation of the tightening member when tightening, the assembling becomes complex for preventing the rotation of the rotation member by an assembling jig or a rotation prevention mechanism.
A need thus exists for a variable valve timing control device which fixes a detection member for detecting a relative rotation phase between a rotation member and a crankshaft with low cost and simple construction.
In light of the foregoing, the present invention a variable valve timing control device which includes a rotation member unitarily fixed to a rotation shaft for opening and closing a valve assembled to a cylinder head of an internal combustion engine to be rotatable, a rotation transmission member engaged with the rotation member to be relatively rotatable, a vane provided on the rotation member or the rotation transmission member, a hydraulic pressure chamber formed between the rotation member and the rotation transmission member and divided into an advance angle chamber and a retarded angle chamber by the vane, and a detection member for detecting a relative rotation phase between the rotation member and a crankshaft. The detection member is press fitted into a cylindrical portion formed in an axial direction of the rotation member and the rotation member is fixed to the rotation member by a tightening member.